At first glance, you might think the S3tr (which is apparently pronounced Streeter) is a knockdown answer to the Segway PT. Like the PT, the S3tr is a compact one-person vehicle driven by a standing rider who balances on a wheeled base and steers with the aid of an upright column. The S3tr has three wheels to the PT's two, but its main advantage is that it folds up, in theory making it more easy to take aboard public transport, or stowing under a desk at work.